1. Field of the Invention
The present invention relates to an electronic weighing apparatus. More specifically, the present invention relates to an electronic weighing apparatus for evaluating the price of an article through multiplication of the measured weight of the article by a preset unit price for displaying the price in a digital manner, which has been adapted such that the price of only the net weight of the article is evaluated through deduction of the tare weight from the gross weight of the article.
2. Description of the Prior Art
In measuring the net weight of an article being weighed, it is necessary to deduct the weight of a container containing the article, i.e. the tare weight, from the measured gross weight. It has been a most typical practice in the prior art for the above described deducting operation that only a tare is first placed on an electronic weighing apparatus of a pulse count type, whereupon the counter is reset to zero upon depression of a reset switch. However, such prior art apparatus has suffered from various shortcomings as enumerated in the following.
(1) In making a zero adjustment of the weighing apparatus, the counter could be reset to zero by depressing the reset switch while the weighing plate of the apparatus is slightly raised by a finger erroneously or intentionally. However, this results in improper zero adjustment. Hence a weight value larger than the actual weight of the article could be obtained and an erroneous price higher than the true net price of the article could be evaluated and displayed.
(2) In initially setting the weight of the tare of an article in the apparatus, only the tare is first placed on the weighing plate of the apparatus and then the reset switch is depressed to reset the counter of the apparatus to zero. In such situation as well, the counter could be reset to zero while the weighing plate with the tare placed thereon is slightly raised by a finger erroneously or intentionally. However, this results in improper deduction of the tare weight. Hence, the weight value corresponding to the said raising of the weighing plate could be added to a true net weight.
(3) Since the tare weight resetting can be made at any time, the deducting operation of the tare weight could be effected repeatedly. Such variation of the tare weight as reset in the apparatus can be observed from the display of a weighing apparatus adapted to display the tare weight to be deducted. Display of such an improper tare weight value makes a customer feel distrustful of the weight measurement. This will be described in more detail by taking examples. Assuming that a tare of 100 g is first placed on the weighing apparatus and the tare weight resetting is made, then the tare weight is displayed as 100 g. Assuming further that the former tare is replaced by another tare of 40 g, display of the weight becomes -60 g. If the tare weight deduction is made in such a situation, display of the reset weight becomes 60 g, in spite of the fact that in actuality the tare of 40 g is placed on the weighing plate of the apparatus, resulting in an error of 20 g.
Now assuming that a tare of 100 g is placed on the weighing apparatus and the tare weight deduction is made, then display of the tare weight first becomes 100 g and display of the weight is reset to zero. Assuming further than another tare of 40 g is additionally placed on the apparatus, display of the weight becomes 40 g. If the tare weight deduction is made in such a situation, display of the tare weight becomes 40 g, in spite of the fact that in actuality the tare of 140 g has been placed on the weighing apparatus, resulting in an error of 100 g in conjunction with the tare weight.